Independently variably controlled pulsed R.F. plasma chemical vapor processing

Abstract

Semiconductive wafers are processed, i.e., etched or layers deposited thereon, by means of a plasma enhanced chemical vapor processing system wherein the plasma is generated by a train of R.F. power pulses. The pulse repetition rate, pulse length and peak power level of the individual pulses are independently variably controlled to variably control the uniformity of the processing of the semiconductive wafers within the processing gaps.

What is claimed is: 
     
       1. In a method for plasma enhanced chemical vapor processing of semiconductive wafers wherein an evacuable envelope contains first and second sets of interleaved electrodes, one set being electrically insulated relative to the other, for establishing an electrical plasma discharge within said evacuable envelope in processing gaps defined between the interleaved electrodes, the steps of: loading semiconductive wafers into the processing gaps;   evacuating said envelope to subatmospheric pressure;   introducing a vapor at subatmospheric pressure into said envelope;   applying pulsed radio frequency power to said first and second sets of interleaved electrodes to establish an electrical plasma discharge at subatmospheric pressure in the processing gaps to produce chemically active vapor products of said plasma discharge;   chemically interacting said chemically active vapor products with said wafers within said processing gaps for processing of said wafers; and   variably controlling the peak power level of the radio frequency power pulses essentially independently of the pulse duration and pulse repetition rate of said pulsed radio frequency power to variably control the distribution of the plasma discharge within said processing gaps for variably controlling the uniformity of the processing of the semiconductive wafers within the processing gaps.   
     
     
       2. The method of claim 1 including the step of: variably controlling the pulse duration of the radio frequency power pulses essentially independently of the peak power level and of the pulse repetition rate of said pulses to variably control the depletion of the reactive vapor products to variably control the uniformity of the processing of the semiconductive wafers within the processing gaps.   
     
     
       3. The method of claim 1 including the step of: variably controlling the pulse repetition rate of the radio frequency power pulses essentially independently of the peak power level and the pulse duration of said pulses to variably control the rate of resupply of the reactive vapor products within said processing gaps to variably control the uniformity of the processing gaps.   
     
     
       4. In a method for plasma enhanced chemical vapor processing of semiconductive wafers wherein an evacuable envelope contains first and second sets of interleaved electrodes, one set being electrically insulated relative to the other, for establishing an electrical plasma discharge within said evacuable envelope in processing gaps defined between the interleaved electrodes, the steps of: loading semiconductive wafers into said processing gaps;   evacuating said envelope to subatmospheric pressure;   introducing a vapor at subatmospheric pressure into said envelope;   applying radio frequency power to said first and second sets of interleaved electrodes to establish an electrical plasma discharge at subatmospheric pressure in said processing gaps to produce chemically active vapor products of said plasma discharge;   chemically interacting said chemically active vapor products with said wafers within said processing gaps for processing said wafers; and   variably controlling the pulse duration of the radio frequency power pulses essentially independently of the peak power level and the pulse repetition rate of said pulses to variably control the depletion of the reactive vapor products in said processing gaps to variably control the uniformity of the processing of the semiconductive wafers within said processing gaps.   
     
     
       5. In a method for plasma enhanced chemical vapor processing of semiconductive wafers wherein an evacuable envelope contains first and second sets of interleaved electrodes, one set being electrically insulated relative to the other, for establishing an electrical plasma discharge within said evacuable envelope in processing gaps defined between said interleaved electrodes, the steps of: loading semiconductive wafers into said processing gaps;   evacuating said envelope to subatmospheric pressure;   introducing a vapor at subatmospheric pressure into said envelope;   applying pulsed radio frequency power to said first and second sets of interleaved electrodes to establish an electrical plasma discharge at subatmospheric pressure in said processing gaps to produce chemically active vapor products of said plasma discharge;   chemically interacting said chemically active vapor products with said loaded wafers for processing of said wafers; and   variably controlling the pulse repetition rate of the radio frequency power pulses essentially independently of the peak power level and the pulse duration of said pulses to variably control the resupply of reactive vapor products within said gaps to variably control the uniformity of the processing of the semiconductive wafers within said processing gaps.   
     
     
       6. In a plasma enhanced chemical vapor processing apparatus for processing semiconductive wafers within an evacuable envelope for containing the plasma enhanced chemical vapor and semiconductive wafers at subatmospheric pressure; first and second sets of electrode means for disposition within the envelope, one set of said electrodes means being electrically insulated from the other, and said first and second sets of electrode means being interleaved with each other for establishing, when energized with electrical potential, an electrical plasma discharge within said evacuable envelope in the processing gaps defined between adjacent ones of said interleaved electrode means;   means for holding semiconductive wafers in said processing gaps;   means for applying pulsed radio frequency power to said first and second sets of interleaved electrodes to establish an electrical plasma discharge at subatmospheric pressure in said processing gaps to produce chemically active vapor products of said plasma discharge for chemically interacting with said wafers within said processing gaps for processing of said wafers; and   means for variably controlling the peak power level of the radio frequency power essentially independently of the pulse duration and the pulse repetition rate of said pulses for variably controlling the distribution of the plasma discharge within said processing gaps for variably controlling the uniformity of the processing of the semiconductive wafers within said processing gaps.   
     
     
       7. The apparatus of claim 6 including, means for variably controlling the pulse duration of the radio frequency power pulses essentially independently of the peak power level and the pulse repetition rate of said pulses to variably control the depletion of the chemically active vapor products within said gaps to variably control the uniformity of the processing of the semiconductive wafers within said processing gaps.   
     
     
       8. The apparatus of claim 6 including, means for variably controlling the pulse repetition rate of the radio frequency power pulses essentially independently of the peak power level and the pulse repetition rate of said pulses to variably control the resupply of the chemically active vapor products within said processing gaps for variably controlling the uniformity of the processing of the semiconductive wafers within said processing gaps.